JPH01288078A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To select a head trace angle to be 180 deg. and to reduce the signal crosstalk by forming a recording part of an audio signal subject to time axis compression only on a track being a part of a track group by one field. CONSTITUTION:A switching means 61 selecting a video signal and an audio signal subject to recording processing and inputting the result to one recording amplifier 6 and a switching means 71 selecting any of signals reproduced by plural heads and inputting the result to one reproducing amplifier 72, are provided and the audio signal subject to time compression is recorded only part of a track group by one field. For example, when one field is split into 3 segments, a PCM audio recording area 81, a video-audio guard area 82, and video signal recording areas 83-85 are provided. Thus, the head trace angle is selected to be 180 deg., many guard areas are not required and disadvantage due to signal crosstalk is reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a rotating head type magnetic recording/reproducing device, and in particular, for video signals, one field of screen is divided into a plurality of segments on the time axis. Later, each segment is recorded on multiple tracks, and the audio signal is recorded on a PC.
A rotary head type magnetic recording and reproducing device that compresses the time axis after M encoding and records it, and when playing back, synthesizes the video signal reproduced from the recording medium on the time axis, and expands the audio signal on the time axis and then decodes it using PCM. This relates to recording and reproducing methods.

[Conventional technology]

FIG. 5 is a diagram showing a rotary head and a magnetic tape of a conventional magnetic recording/reproducing apparatus (hereinafter referred to as a VTR) that encodes an audio signal by PCM and then performs time axis compression for recording.
In the figure, 2 is a tape wrapped around a rotating drum 3;
Magnetic heads la and lb are attached to face the rotating drum 3 at an angular interval of 180 degrees. FIG. 6 shows a track pattern recorded by the conventional method as described above. The conventional example shown here is a VTR that records one field on one track, but the track arrangement for each segment of a VTR that records one field by dividing it into multiple segments is also the same, so the following describes the case of one track per field. I will explain about it.

FIG. 7 is a circuit block diagram of the recording system of the above conventional apparatus. In the figure, 10 is an audio signal input terminal, 11 is a PCM encoder, 12 is a recording PCM signal processing circuit, and 13.14 is a time axis compression circuit. 1st. second memory, 15 modulator, 16
17 is a video signal input terminal, 17 is a recording video signal processing circuit, and 18 is a video signal input terminal.
Reference numeral 19.20 indicates a first switch for switching the head for recording the recorded video signal and audio signal, and 19.20 indicates a first and second recording amplifier.

FIG. 8 is a circuit block diagram of the reproduction system of the above-mentioned conventional device, in which 30 is a second switch for switching the head to be reproduced, 31 is a first reproduction amplifier, 32 is a reproduction video signal processing circuit, 33 is a video signal output terminal, 34 is a second
35 is a demodulator, 36 is a reproduction PCM signal processing circuit, and 37° and 38 are a third . A fourth memory, 39 is a PCM decoder, and 40 is an audio signal output terminal.

Further, FIG. 9 is a timing diagram of the recording and reproducing system.

Next, the operation will be explained.

During recording, the audio signal S input from the audio signal input terminal 10 shown in FIG.
and At, the PCM signal is colored by the PCM encoder 11, and the PCM signal S is recorded by the PCM signal processing circuit 12.
Through the period D1 and D shown in FIG. 9(d), (el)
2 is stored in the first memory 13 and the second memory 14. Here, during periods A1 and A2, the rotating drum 3 is 180
After that, an error correction and detection code is added in the recording PCM signal processing circuit 12. This process is performed during the period P1 shown in FIG. 9(d) and (el).
and Pg. When the encoding such as error correction is completed, the signal is read out from the first memory 13 or the second memory 14 with the time axis compressed, and the signal is modulated by the modulator 15.

On the other hand, a video signal Sv is input from the video signal input terminal 16, and the recording video signal processing circuit 17 performs FM modulation of the luminance signal and low frequency conversion of the color subcarrier signal.

Here, it is assumed that the video signal subjected to recording signal processing is Sq.

During the "L" period of the signal Vs (see FIG. 9) indicating the rotational phase of the drum at the first switch 18, the head 1a outputs the audio signal S, . . . and the head 1b outputs the video signal Sc&. During the period of "H", the head 1a outputs the video signal SQ, and the head 1b outputs the audio signal S, respectively. The signal is switched to be recorded on the tape via the second recording amplifier 19, 20. In FIG. 9, these signals are recorded by the head 1a as S r l *
S Q I, the signal recorded by head 1b is
rz, SQt (same figure (illustration, (hl,
01. (g))).

The pattern of audio tracks and video tracks recorded in this manner is formed as shown in FIG.

The track pattern shown in FIG.
This was created with reference to the content published on page 172 of MM C0NFER-ENCE) J (May 1986). From the bottom of tape 2, 51 is the clock.
52 is a run-in area, 52 is a PCM audio recording area, 53 is an after-recording margin, 54 is a video overlap area, and 55 is a video signal recording area. The length that the head traces over these areas is expressed as the rotation angle of the drum: NT
For SC, 2.06 degrees, 26.32 degrees, respectively.
They are 2.06 degrees, 2.62 degrees, and 180 degrees.

During reproduction, the signal S□*Sri+SQI+sQ□ reproduced from each of the heads la and lb is the signal ■.

The video signal 5QII Sq't passes through the first reproducing amplifier 31 and becomes the original video signal by the reproduced video signal processing circuit 32.
The video signal is output from the video signal output terminal 33.

On the other hand, the audio signal Srl+Sr1 is demodulated by the demodulator 35 via the second reproduction amplifier 34, and the demodulated signal is output to the reproduction P
A signal S P l rSF is sent to the third memory 37 and the fourth memory 38 through the CM signal processing circuit 36, respectively.
is stored as . Thereafter, error correction, correction, etc. are performed during periods Q and Q shown in FIGS. 9(1) and (e). After the error correction is completed, each memory 37 is expanded during the period shown in the same figure and in D2 while expanding the time axis.
．． 38, the signals are converted into analog audio SP by the PCM decoder 39, and output to the audio signal output terminal 40 during periods AI and Ai shown in FIG. 9(n).

[Problem to be solved by the invention]

Conventional magnetic recording and reproducing devices are configured as described above, so a guard area is provided for separating the video signal area and audio signal area for each recording track, and an area is provided to provide tracking margin during dubbing. This is disadvantageous in terms of effective use of recording tracks.

Furthermore, since each head traces the tape over 180 degrees, there is always a period when both heads simultaneously record and play back different signals, so a recording amplifier and a playback amplifier must be provided for each head. In addition, there was a design drawback in that signal crosstalk between the two signals was likely to occur.

Furthermore, although the above conventional example shows a VTR that records one field and one track, in the case of a VTR that records one field by dividing it into multiple tracks, based on the conventional example, the audio signal is recorded in multiple tracks as well as the video signal. This poses a problem in that the time axis compression/expansion processing and design considerations for signal crosstalk are much more complicated than in one-field, one-track recording.

This invention has been made in view of the above-mentioned problems, and uses tape more effectively than conventional methods, while allowing the tape head trace angle to be 180 degrees, and is a rotation system that records one field by dividing it into multiple tracks. The purpose is to obtain a head type magnetic recording/reproducing device.

[Means to solve the problem]

The magnetic recording and reproducing apparatus according to the present invention includes a switching means for selecting a recorded video signal and an audio signal and inputting the same to one recording amplifier, and selecting one of the signals reproduced by a plurality of heads. and a switching means for inputting the audio signal to one playback amplifier, and a section for recording the time-axis compressed audio signal is provided not for each track but only for some tracks of a group of tracks for one field. This is how it was done.

[Effect]

In this invention, the recording portion of the time-compressed audio signal is formed only on some tracks of the track group for one field, so that the head trace angle can be increased to 18
It can be set to 0 degrees, and signal crosstalk can be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a recording system circuit of a VTR according to an embodiment of the present invention, and FIG. 2 is a block diagram of a reproduction system circuit. 61 is a switch for switching between a recorded video signal and an audio signal, 62 is a recording amplifier, 71 is a switch for selecting one of the signals reproduced by heads la and lb, and 72 is a reproduction amplifier.

FIG. 3 shows a track pattern when one field is divided into three segments according to this embodiment, one track is assigned to each segment, and a time-compressed audio signal is recorded on only one of the segments. It is a diagram. In this figure, from the lower end of the tape 2 toward the head running direction, 81 is a 20M audio recording area, 82 is a video-audio guard area, and 83, 84, and 85 are video signal recording areas. The drum rotation angle per track is 180 degrees.

For example, in the case of an NTSC signal, if the audio signal is time-compressed and recorded within the vertical blanking period, the length of the PCM audio recording area 81 will be 41 degrees in drum rotation angle, as shown in FIG.

FIG. 4 is an operation timing diagram of the device according to this embodiment.

Next, the operation will be explained.

First, the operation during recording will be explained. Audio signal SA input from terminal 10 of the circuit shown in Fig. 1 (Fig. 4 (e)
) is converted into a digital signal SA by the PCM encoder 11.
, and is stored in the first memory 13 during the period D1 shown in FIG. 4(dl) and in the second memory 14 during the period D2 shown in FIG. 4(fl) through the recording PCM signal processing circuit 12. .The signals stored in each memory 13 and 14 are each added with a code for error correction and detection during periods P and 9P2 shown in (di, (e)) of the same figure.The signals processed here are , are time-compressed when read out from each memory 13, 14, and placed at the position shown in FIG.

On the other hand, the video signal Sv input from the input terminal 16 is subjected to processing such as FM modulation of the luminance signal and low frequency conversion of the color subcarrier signal by the recording video signal processing circuit 17. Figure 4 (a
) indicates the video signal Sv, and the shaded portion indicates the vertical blanking period, into which the time-compressed audio signal is inserted.

The combination of the video signal and the audio signal is performed by switching the changeover switch 61 according to the changeover signal AVSW shown in FIG.

Furthermore, since one field of the video signal is divided into three segments, each segment is recorded on three tracks as shown in FIG. 4 (TI), (J), and Ck).

Next, the operation when reproducing a signal recorded using the above method will be explained. During reproduction, the signals reproduced from each head air a and lb are head switching signals H shown in FIG. 4(b).
3W, the video signal component is sent to the playback video signal processing circuit 32 and the audio signal component is sent to the demodulator 35 via the playback amplifier 72.

First, since the audio signal is played back from the head at the same timing as during recording, the signal must be subjected to time axis expansion and movement processing using the third and fourth memories 37 and 38. . For example, the audio signal reproduced by the head 1a is subjected to error correction, correction, etc. by the reproduction PCM signal processing circuit 36 during the period Q in FIG. 4(1).
During the period D1, the PCM decoder 39 converts the analog audio signal Sapm (A+ portion) shown in FIG.

On the other hand, the video signal portion is reproduced in the reproduced video signal processing circuit 32, but since no particular time axis companding processing is performed during recording, only three tracks are sequentially connected. However, since the vertical blanking period is removed during recording, this portion must be added. Since the waveform of the vertical blanking period is constant according to the standard regardless of the pattern within the effective screen, it is necessary to store the data of the vertical blanking period in ROM (read-only memory) in advance and read and add it to each field. Then, processing such as FMfi tone of the luminance signal and high frequency conversion of the color subcarrier signal is performed and outputted to the video signal output terminal 40.

In this way, in the device of this embodiment, the time-compressed audio signal is provided only in a part of the track group representing one field, so the head trace angle can be 180 degrees, and the head tracing angle can be set to 180 degrees. No guard area is required, and inconveniences due to signal crosstalk can be reduced.

In the above embodiment, an example was shown in which one field is divided into three tracks and recorded, but when one field is simultaneously recorded by arbitrary n heads and divided into nxm tracks (n, m is an integer).

〔Effect of the invention〕

As described above, according to the present invention, there is provided a switching means for selecting a recorded video signal and an audio signal and inputting the same into one recording amplifier; A switching means for selectively inputting it to one playback amplifier is provided, and the time-compressed audio signal is recorded only in a part of the track group corresponding to one field, so that the audio signal area is changed for each track. It is possible to obtain a magnetic recording and reproducing device that effectively utilizes tape, which does not require the provision of a head trace angle and which only requires a head trace angle of 180 degrees.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a recording system of a VTR according to an embodiment of the present invention, FIG. 2 is a block diagram of a reproduction system of the VTR, and FIG. 3 is a diagram showing a recording track pattern on a tape by the VTR. , FIG. 4 is a timing chart of each signal during recording/reproduction of the VTR, FIG. 5 is a diagram showing the relationship between the rotary head of the conventional device and the magnetic tape, and FIG. 6 is a diagram showing the recording track pattern thereof. , FIG. 7 is a circuit block diagram of a conventional recording system, FIG. 8 is a circuit block diagram of a conventional reproduction system, and FIG. 9 is a timing diagram of each signal during recording/reproduction of the conventional system. 61 and 71 are switches, and 62 is a recording amplifier (72 is a reproduction amplifier. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) For video signals, one field of screen is divided into multiple segments on the time axis, and each segment is recorded on multiple tracks, and for audio signals, P
After CM encoding, the video signal is compressed on the time axis and recorded, and during playback, the video signals reproduced from the recording medium are synthesized on the time axis.
In a rotary head type magnetic recording and reproducing device that expands the time axis of the audio signal and then decodes it using PCM, a switching means for selecting the video signal and audio signal that have been recorded and inputting them to one recording amplifier, and a plurality of A switching means is provided for selecting one of the signals reproduced by the head and inputting it to one reproduction amplifier, and an audio signal recording area is formed only in some tracks of a group of tracks representing one field of screen. A magnetic recording/reproducing device characterized in that it records a signal so as to read a signal.